358 CONTRIBUTIOISrS FROM THE NATIONAL HERBARIUM. 



D. Pinnae 1 to 4 pairs. 



Leaflets one pair 54. M. zygophylla. 



Leaflets 2 or more pairs. 



Valves of the fruit armed with spines. 



Rachis of the leaf armed with numerous spines. 



55. M. hystricosa. 

 Raehis of the leaf unarmed. 



Leaflets green, thinly sericeous 56. M. monancistra. 



Leaflets white with a dense sericeous pubescence. 



57. M. emoryana. 

 Valves of the fruit unarmed, the margins often spiny. 



Corolla nearly glabrous 58. M. lindheimeri. 



CoroHa densely pubescent. 



Spines straight; leaflets densely sericeous with long soft 



hairs 59. M. purpusii. 



Spines recurved ; leaflets strigillose or sericeous with very 

 short hairs. 



Pinnae 3 or 4 pairs 65. M. biuncifera. 



Pinnae 1 or 2 pairs. 



Fruit glabrate, acute at the base 60. M. pringlei. 



Fruit densely tomentose, rounded at the base. 



Fruit strongly constricted between the seeds, the 

 margins with numerous long spines. 



61. M. depauperata. 

 Fruit scarcely at all constricted, the margins un- 

 armed or nearly so 62. M. calcicola. 



DD. Pinnae more than 4 pairs in all or most of the leaves. 

 Leaflets about 1 mm. long. Valves of the fruit very spiny. 



63. M. minutifolia. 

 Leaflets 2 mm. long or longer. 



Leaflets 2.5 to 3 mm. wide, densely piloso-sericeous on both 



surfaces 64. M. mollis. 



Leaflets mostly less than 2 mm. wide. 



Fruit acute or acutish at liase and usually nlso at apex, 



4 to 6 mm. wide 65. M. biuncifera. 



Fruit rounded or very obtuse at base and apex, 7 to 10 mm. 

 wide. 



Leaflets 5 to 7 mm. long 66. M. lemmonl. 



Leaflets 4 to 5 mm. long 67. M. aculeaticarpa. 



1. Mimosa spirocarpa Rose, Contr. U. S. Nat. Herb. 3: 316. pL 11. 1895. 

 Sinaloa to Colima ; type from Culiacdn, Sinaloa. 



Shrub, 3 to G meters high ; leaflets obliquely oval or suborbicular, 1 to 3 cm. 

 long; flowrrs purplish at first, becoming white, the spikes 7 to 13 cm. long; 

 fruit narrow, coiled lilie a snail shell. 



2. Mimosa rosei Robinson, Proc. Amer. Acad. 33: 317. 1S98. 

 Known only from the type locality, Bolanos, Jalisco. 



Plant unarmed, so far as specimens show ; leaflets obliquely obovate or oval ; 

 fruit pale green, about 7 cm. long and 7 mm. wide, glabrous, unarmed, long- 

 stipitate. 



3. Mimosa paucifoliolata Micheli. Mem. Soc. Phys. Hist. Nat. Gen6ve 34: 278. 



pi. 2/,. 1903. 

 Mimosa laxifiora .sygophijUohles Robinson, Proc. Amer. Acad. 33: 317. 1898. 

 Colima and Michoacj'm or Guerrero ; type from Las Minitas. 



